This invention relates to an information transport system using existing telephone lines and, more particularly, to the interconnecting of a communication system to the telephone lines via multiplexing circuitry. The multiplexing circuitry bypasses telephone central-office switching equipment to permit customers of the system, such as gas, water and other utilities, to transmit data directly between the customer and numerous telephone subscribers.
The premises of telephone subscribers generally have sources of data which may be processed automatically by users of the data. For example, subscriber premises may have electric meters, gas meters, water meters and other devices having a metered output of usage such as pay television. The foregoing customers process the data provided by the meters for billing purposes. Of course, the customers must have some method of obtaining the data from the meters.
Currently, two methods of obtaining the data are available. One method, a representative of the customer visits the subscriber premises to read the meter. Separate representatives may be dispatched for the reading of gas and water meters. The second method is useful only in some locations where meters are provided with encoding equipment which converts the meter reading to electric signals which can be transmitted over the telephone lines. Then, the meters can be read by use of the telephone system whereby automatic dialing equipment dials the number of the meter which is to be read, and transmits command signals to activate the encoder to transmit the meter reading. The second method thus entails a two-way transmission of control and data signals via the telephone lines and the central-office switching equipment.
The foregoing methods of obtaining and transmitting data suffer disadvantages and introduce problems. The first method employing the manual reading and manual data transmission requires additional personnel to read the meters.
The second method, employing automatic reading and data transmission, is advantageous in that existing subscriber telephone lines are employed, and in that new lines do not have to be built. However, the second method may overload the central-office switching, particularly if employed during business hours when telephone usage is high. In addition, the second method experiences delays of the switching equipment in establishing a telephone circuit. Both methods however, are much slower than modern communication systems which transports many forms of data.